1. Field of the Invention
Embodiments of this invention generally relate to displaying oblique imagery.
2. Related Art
Photographers often take images of the Earth from altitude, such as from an aircraft. Such aerial photographs can be taken from different perspectives. For example, nadir photographs are taken from a camera oriented straight down towards the Earth. While nadir photographs offer advantages, their steep perspective limits what they capture. For example, nadir photographs often fail to capture the sides of buildings, primarily capturing their roofs.
Oblique photographs, on the other hand, are taken with cameras tilted relative to the surface of the Earth. Often, oblique photographs are tilted by approximately 45 degrees. In contrast to nadir images, oblique photographs capture the sides of buildings. For this reason, oblique photographs are often used, for example, in real estate applications.
In one example, oblique images are available from a BING maps service, available from Microsoft, Inc. The BING maps service has a feature referred to as “Bird's Eye View” that displays an oblique image from the viewport of the camera that captured the image. While this approach has advantages, there are at least two drawbacks. First, because images can only be shown one at a time, navigation between images is difficult. To navigate between images, the BING maps service fades one image out, and another nearby image fades in. Similarly, the BING maps service does not allow a user to zoom out to an area covered by more than one image. Second, overlaying map data, such as roads, is difficult, because the map data must be positioned in the coordinate space of each image. This requires a great deal of additional processing time and storage.
Systems and methods are needed better to display oblique imagery with overlaid map data.